error is using bvpset in bvp4c

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Syed
Syed el 24 de Sept. de 2024
Comentada: Syed el 25 de Sept. de 2024
Hi, I am Syed,
I like to have an output with 6 or more than 6 decimal place (for example: 3.033334), without bvpset i am getting the output upto 4 decimal places, but i like to have upto to 6 or 8 decimal places, please guide me to get the desired output
The error i am getting is
Error using <=
Not enough input arguments.
My program is given below
close all
clc
phi=0.1;
phi1=2;
phi2=2;
Betaf=0.00021;
Betas=0.000058;
sigmaf=0.005;
sigmas=580000;
GR=2;
EM2=20;
Rof=997.1;
Ro=5;
c=0;
Ros=4420;
h=0.5;
Hc=0.25;
K=1;
R=1;
e1=(1./((1-phi).^2.5));
e2=(1-phi)+(phi.*(Ros./Rof));
e3=(1-phi)+phi.*((Ros.*Betas)./(Rof.*Betaf));
sigma=(sigmas./sigmaf);
e4=1-((3*(1-sigma).*phi)./((2+sigma)+(1-sigma).*phi));
gama1=e2./e1;
gama2=1/e1;
gama3=e3./e1;
s1=(e4./(phi1.*(1-i.*Hc)));
s2=(e4./(phi2.*(1-i.*Hc)));
dydx=@(x,y)[y(3);
y(4);
-EM2.*gama2.*y(4)+2.*i.*Ro.*gama1.*y(1)+gama3.*GR.*x+R.*gama1;
(-e4./(1-i.*Hc)).*y(3)];
BC = @(ya,yb)[ya(1);yb(1)-c;ya(4)-s1.*ya(2);yb(4)+s2.*yb(2)];
yinit = [0.01;0.01;0.01;0.01];
options = bvpset('stats','on','RelTol',le-3);
solint = bvpinit(linspace(0,1,50),yinit,options);
U1 = bvp4c(dydx,BC,solint);
dudy1=U1.y(3,1)

Respuesta aceptada

Shashi Kiran
Shashi Kiran el 24 de Sept. de 2024
Hi @Syed,
I understand that you are aiming to obtain an output with 6 or more decimal places but are encountering errors.
Here are my observations and corrections for your code:
  • The error was because le-3 is not a valid expression. It should be 1e-3, which is the proper MATLAB syntax for .
options = bvpset('stats','on','RelTol',1e-3);
  • The bvpinit function is used to initialize the solution guess and mesh, and it doesn't accept the options structure as an argument.
solint = bvpinit(linspace(0,1,50),yinit);
  • The correct place to pass the options structure is in the bvp4c function call. This allows the solver to use the relative tolerance (RelTol) and print statistics ('stats', 'on').
U1 = bvp4c(dydx,BC,solint,options);
Here is the output following these corrections:
Refer to the following documentations for more details about the functions:
  1. bvpset: https://www.mathworks.com/help/matlab/ref/bvpset.html
  2. bvpinit: https://www.mathworks.com/help/matlab/ref/bvpinit.html
  3. bvp4c: https://www.mathworks.com/help/matlab/ref/bvp4c.html
Hope this solves your query.
  4 comentarios
Shashi Kiran
Shashi Kiran el 25 de Sept. de 2024
Additionally,
To set the default formatting for long in MATLAB, follow these steps:
- On the MATLAB homepage, go to Home.
- Navigate to Preferences.
- Under Command Window, select Text Display, then choose Numeric Format and set it to long.
Syed
Syed el 25 de Sept. de 2024
I got it now, thanks a lot

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